Method and apparatus having plate electrode for surface treatment using capillary discharge plasma

ABSTRACT

A method and an apparatus for treating a workpiece using a plasma discharge are disclosed in the present invention. In treating a workpiece using a plasma discharge, the apparatus includes at least one plate electrode electrically coupled to a power source, a dielectric body having first and second sides, wherein the first side is coupled to the at least one plate electrode and the second side has at least one capillary extending substantially therethrough in a direction of the first side of the dielectric body, and a counter electrode electrically coupled to the power source.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a plasma discharge apparatus, and more particularly to a method and an apparatus having at least one plate electrode for surface treatment using capillary discharge plasma shower. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for plasma treatment of workpieces under an atmospheric pressure or a higher pressure, thereby providing virtually unrestricted applications regardless of size of the workpieces.

[0003] 2. Discussion of the Related Art

[0004] A plasma discharge has been widely used for treating surfaces of a variety of workpieces in many different industries. Particularly, stations for cleaning or etching electronic components such as a printed circuit boards (PCB), lead frames, microelectronic devices, and wafers, have been employed in electronics industries since they provide advantages over the conventional chemical cleaning apparatus. For example, the plasma process occurs in a closed system rather than in an open chemical bath. Thus, the plasma process may be less hazardous and less toxic than the conventional chemical process. One example of a related background art plasma process and apparatus was disclosed in U.S. Pat. No. 5,766,404.

[0005] Another example of the related background art was disclosed in “Surface Modification of Polytetrafluoroethylene by Ar+ Irradiation for Improved Adhesion to Other Materials”, Journal of Applied Polymer Science, pages 1913 to 1921 in 1987, in which the plasma process was applied on the surfaces of plastic workpieces in an effort to improve wetability or bonding of the workpieces.

[0006] All the background art plasma processes, however, have to be carried inside a treatment chamber because the background art plasma processes can only be performed under a vacuum condition. Thus, when a workpiece is too big to be treated in the chamber, the background art plasma process cannot be used to treat the workpiece. As a result, the background art plasma processes are very limited in applications.

SUMMARY OF THE INVENTION

[0007] Accordingly, the present invention is directed to a method and an apparatus for plasma treatment using capillary discharge plasma that substantially obviate one or more of the problems due to limitations and disadvantages of the related art.

[0008] Another object of the present invention is to provide a method and an apparatus for plasma treatment using capillary discharge plasma which can be applied in sterilization, cleaning, etching, surface modification, or deposition of thin film under a high pressure or an atmospheric pressure condition.

[0009] Additional objects and advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

[0010] To achieve the objects and in accordance with the purpose of the invention, as embodied and broadly described herein, an apparatus for treating a workpiece using a plasma includes at least one plate electrode electrically coupled to a power source, a dielectric body having first and second sides, wherein the first side is coupled to the at least one plate electrode and the second side has at least one capillary extending substantially therethrough in a direction of the first side of the dielectric body, and a counter electrode electrically coupled to the power source.

[0011] In another aspect of the present invention, an apparatus for treating a workpiece using a plasma includes at least one plate electrode electrically coupled to a power source, a dielectric body comprising at least one capillary extending therethrough thereby exposing portions of the plate electrode to the workpiece, a counter electrode electrically coupled to the power source, and a dielectric plate electrically coupled to the counter electrode.

[0012] In another aspect of the present invention, an apparatus for treating a workpiece using a plasma includes at least one plate electrode electrically coupled to a power source, a dielectric body coupled to the at least one plate electrode, a dielectric plate coupled to the dielectric body, a counter electrode surrounded by the dielectric plate and the dielectric body, and electrically coupled to a power source, and at least one capillary extending through the dielectric plate, the counter electrode and the dielectric body.

[0013] Furthermore, the apparatus can automatically treat several workpieces by placing the workpieces on a conveyer that carries the workpieces under the plasma.

[0014] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are needed to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.

[0016] In the drawings:

[0017]FIG. 1A is a simplified schematic cross-sectional view of a capillary discharge plasma apparatus according to one embodiment of the present invention;

[0018]FIG. 1B is a detailed cross-sectional view of a capillary discharge plasma apparatus shown in FIG. 1A;

[0019]FIG. 1C is a detailed cross-sectional view of the capillary discharge plasma apparatus shown in FIG. 1B enclosed in a chamber;

[0020]FIG. 2A is a simplified schematic cross-sectional view of a capillary discharge plasma apparatus according to another one embodiment of the present invention;

[0021]FIG. 2B is a detailed cross-sectional view of a capillary discharge plasma apparatus shown in FIG. 2A;

[0022]FIG. 2C is a detailed cross-sectional view of the capillary discharge plasma apparatus shown in FIG. 2B enclosed in a chamber;

[0023]FIG. 3A is a simplified cross-sectional view of another embodiment of the apparatus of the present invention;

[0024]FIG. 3B is a detailed cross-sectional view of the apparatus shown in FIG. 3A;

[0025]FIG. 3C is a detailed cross-sectional view of the apparatus shown in FIG. 3B enclosed in a chamber;

[0026]FIG. 3D is a plane view of the capillary discharge plasma head of the apparatus shown in FIGS. 3A to 3C; and

[0027]FIG. 3E is a partial cross-sectional view of the capillary discharge plasma head shown in FIG. 3D.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0028] Reference will now be made in detail to the present illustrated embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0029]FIG. 1A is a schematic cross-sectional view of an embodiment of a capillary discharge plasma head for surface treatment for conductive workpieces. The apparatus includes at least one plate electrode 141, a dielectric body 142, at least one capillary 143 formed in the dielectric body 142 and extending substantially therethrough, and a counter-electrode 145, wherein a workpiece 144 is placed. The apparatus discharges plasma through the capillaries and onto the conductive workpiece 144. Throughout the present invention, the plate electrode 141 may consist of more than one plate. Moreover, there is no critical geometry for the plate electrode 141 as long as the plate electrode matches all of the capillaries.

[0030]FIG. 1B shows a detailed cross-sectional view of the apparatus shown in FIG. 1A. In addition to the elements described above, FIG. 1B shows a power source 150. The power source may be either AC or DC and is electrically connected to the plate electrode 141 and to the counter electrode 145. Furthermore, the power source is grounded. Referring back to the dielectric body 142, although there are no critical limitations as to a thickness of the dielectric body 142, the thickness of the dielectric body 142 may be in the range of about 1 mm to 3 cm. A diameter of each capillary may be in the range of about 0.2 mm to 0.8 mm. A cross-sectional shape of the capillary may have any kind of geometry including a circular or polygonal shape. An operation power may be in the range of 5,000 volts to 10,000 volts at 10 to 150 kHz.

[0031] A conductive substrate 144 is placed under the capillary plasma discharge head and over the counter electrode 145 and is subjected to a plasma treatment. As illustrated in FIG. 1B, a portion of the dielectric body 142 separates the plate electrode 141 from the capillaries 143, thereby preventing a glow-to-arc transition in treating the conductive workpiece.

[0032]FIG. 1C illustrates a schematic cross-sectional view of the apparatus illustrated in FIG. 1B housed in a chamber 146. The chamber 146 has at least two openings 147 and 148 that allow gases to be provided and removed from the chamber. Any type of gas or gases may be provided into the chamber such as Ar, He, oxygen and air, if desired. Any gas or gases can be provided and removed from the chamber. Moreover, it is not necessary to create vacuum in the chamber 146 to treat a workpiece 144. This is because the apparatus utilizes high efficiency capillary discharge plasma. All that is necessary to treat a workpiece is an isolated space for maintaining a certain working pressure. Furthermore, the chamber 146 allows treating the workpiece 144 under a working gas environment.

[0033]FIG. 2A shows a simplified cross-sectional view of another embodiment of the present invention for surface treatment for non-conductive workpieces. The apparatus includes at least one plate electrode 151, a dielectric body 152, at least one capillary 153 formed in the dielectric body 152 and extending therethrough. The apparatus furthermore includes a counter-electrode 155, a dielectric plate 156, and a non-conductive workpiece 154 placed over the dielectric plate 156. The apparatus generates plasma through the capillaries directed to the non-conductive workpiece 154.

[0034]FIG. 2B shows a detailed cross-sectional view of the apparatus shown in FIG. 2A. In addition to the elements described above, FIG. 2B shows a power source 160. The power source is electrically connected to the plate electrode 151 and to the counter electrode 155. Furthermore, the power source is grounded. Referring back to the dielectric body 152, although there are no critical limitations as to the thickness of the dielectric body 152, a thickness of the dielectric body 152 may be in the range of about 1 mm to 3 cm. A diameter of each capillary may be in the range of about 0.2 mm to 0.8 mm. A nonconductive workpiece 154 is placed under the capillary plasma discharge head and over the dielectric plate 156 and is subjected to a capillary plasma discharge. The dielectric plate 156 is placed over the counter electrode 155. As illustrated in FIG. 2B the plate electrode 152 is exposed by the capillaries 153.

[0035]FIG. 2C shows a detailed cross-sectional view of the apparatus shown in FIG. 2B, enclosed in a chamber 157. The chamber 157 has at least two openings 158 and 159 that allow gases to be provided and removed from the chamber. Any type of gas or gases may be provided into the chamber such as Ar, He, oxygen and air, if desired. Although any gas or gases may be provided and removed from the chamber, it is not necessary to create vacuum in the chamber 157 to treat workpiece 154. This is because the apparatus utilizes high efficiency capillary discharge plasma. All that is necessary to treat a workpiece is an isolated space for maintaining a certain working pressure. Furthermore, the chamber 157 allows treating workpiece 154 under a working gas environment.

[0036]FIG. 3A shows a simplified cross-sectional view of another embodiment of the present invention for surface treatment for conductive, semi-conductive, and non-conductive workpieces. A detailed description of the components of this embodiment will be discussed below.

[0037]FIG. 3B shows a detailed cross-sectional view of FIG. 3A. The apparatus includes at least one plate electrode 161, a dielectric body 162, capillaries 163, a counter electrode 165, a dielectric plate 166, a workpiece 164 and a power source 170. The power source 170 is electrically connected to the plate electrode 161 and to the counter electrodes 165. Unlike FIGS. 2A to 2C, an additional dielectric plate for placing the workpiece is not necessary in this embodiment.

[0038]FIG. 3B is a schematic cross-sectional view of the apparatus illustrated in FIG. 3A utilized for plasma surface treatment for one of conductive, semiconductive, and non-conductive workpieces. The apparatus includes an AC power supply 170, at least one plate electrode 161, a dielectric body 162, capillaries 163, a counter electrode 165, and a dielectric plate 166. The counter electrode 165 is encapsulated by the dielectric body 162 and the dielectric plate 166, and is electrically connected to the power supply 170. The capillaries 163 are formed in the dielectric body 162 and in the dielectric plate 166, and extend therethrough, permitting the plate electrode 161 to be exposed by the capillaries 163. The AC power supply 170 has one of its terminals connected to the plate electrode 161, and the other terminal connected to the counter electrode 165 and grounded. The capillaries 163 formed in the dielectric body 162 may range in number from one to thousands depending upon the dimension of the dielectric body 162. A thickness of the dielectric body 162 including the dielectric plate 166 may be in the range of about 1 mm to 3 cm. A diameter of each capillary is may be in the range of about 0.2 to 0.8 mm. In the present apparatus, any kind of workpiece, including conductive, semiconductive, and non-conductive can be treated. The dielectric body 162 and the dielectric plate 166 may be formed of a single body.

[0039]FIG. 3C shows a detailed cross-sectional view of the apparatus shown in FIG. 3B, enclosed in a chamber 167. The chamber 167 has at least two openings 168 and 169 that allow gases to be provided and removed from the chamber. Any type of gas or gases may be provided into the chamber such as Ar, He, oxygen and air, if desired. Although any gas or gases can be added and removed from the chamber, it is not necessary to create vacuum in the chamber 167 to treat the workpiece 164. This is because the apparatus utilizes high efficiency capillary discharge plasma. All that is necessary to treat a workpiece is an isolated space for maintaining a certain working pressure. Furthermore, the chamber 167 allows treating the workpiece 164 under a working gas environment.

[0040]FIG. 3D shows a plane view of the capillary discharge plasma head as viewed from the bottom without the dielectric plate 166. The capillary discharge plasma head includes a dielectric body 162, capillaries 163 and a counter electrode 165.

[0041]FIG. 3E shows a partial cross-sectional view of the capillary discharge plasma head shown in FIG. 3B. A portion of the dielectric plate 166 is not illustrated to show more clearly the counter electrode 165. The counter electrode 165 is placed over the dielectric body 162 and comprises a plurality of openings substantially aligned with the capillaries 163. The capillaries 163 extend through the dielectric body 162, the counter electrode 165 and the dielectric plate 166, and are where plasma is discharged.

[0042] Although the capillaries are shown to be in a parallelogram shape in this embodiment, the capillaries may be formed in any shape in the dielectric body. In the present embodiment, in order to improve efficiency in treating the workpiece, the capillaries are shown to form a parallelogram shape. However, there may be other geometries that improve efficiency. By forming the dielectric body in a parallelogram shape, none of the plasma beam emerging from the capillaries overlaps one another in the moving direction of the workpiece plate on a conveyor.

[0043] Finally, FIG. 3D illustrates the plate electrode 161 contacting the dielectric body 162 and the capillaries 163 producing a capillary plasma discharge.

[0044] It will be apparent to those skilled in the art that various modifications and variations can be made in the method and apparatus having a plate electrode for surface treatment using capillary discharge plasma shower of the present invention without departing from the scope or spirit of the invention. Thus, it is intended that the present invention covers the modifications and variations of the invention provided they come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. An apparatus for treating a workpiece using a plasma, comprising: at least one plate electrode electrically coupled to a power source; a dielectric body having first and second sides, wherein the first side is coupled to the at least one plate electrode and the second side has at least one capillary extending substantially therethrough in a direction of the first side of the dielectric body; and a counter electrode electrically coupled to the power source.
 2. The apparatus according to claim 1, wherein the dielectric body has a thickness in the range of about 1 mm to 3 cm.
 3. The apparatus according to claim 1, wherein the at least one capillary has a diameter in the range of about 0.2 mm to 0.8 mm.
 4. The apparatus according to claim 1, wherein the workpiece is placed between the at least one plate electrode and the counter electrode.
 5. The apparatus according to claim 1, wherein the workpiece is conductive.
 6. The apparatus according to claim 1, further comprising a chamber for treating the workpiece under a working gas environment.
 7. The apparatus according to claim 6, wherein the chamber includes at least one gas input opening and at least one gas output opening.
 8. The apparatus according to claim 1, wherein the capillary in the dielectric body is located to have a parallelogram shape.
 9. An apparatus for treating a workpiece using a plasma, comprising: at least one plate electrode electrically coupled to a power source; a dielectric body comprising at least one capillary extending therethrough thereby exposing portions of the plate electrode to the workpiece; a counter electrode electrically coupled to the power source; and a dielectric plate electrically coupled to the counter electrode.
 10. The apparatus according to claim 9, wherein the dielectric body has a thickness in the range of about 1 mm to 3 cm.
 11. The apparatus according to claim 9, wherein the at least one capillary has a diameter in the range of about 0.2 mm to 0.8 mm.
 12. The apparatus according to claim 9, wherein the workpiece is placed between the at least one plate electrode and the counter electrode.
 13. The apparatus according to claim 9, wherein the workpiece is non-conductive.
 14. The apparatus according to claim 9, further comprising a chamber for treating the workpiece under a working gas environment.
 15. The apparatus according to claim 14, wherein the chamber includes at least one gas input opening and at least one gas output opening.
 16. The apparatus according to claim 9, wherein the capillary in the dielectric body is located to form a parallelogram shape.
 17. An apparatus for treating a workpiece using a plasma, comprising: at least one plate electrode electrically coupled to a power source; a dielectric body coupled to the plate electrode; a counter electrode embedded in the dielectric body, and electrically coupled to a power source; and at least one capillary extending through the dielectric plate, counter electrode and dielectric body.
 18. The apparatus according to claim 17, wherein the dielectric body has a thickness in the range of about 1 mm to 3 cm.
 19. The apparatus according to claim 17, wherein the at least one capillary has a diameter in the range of about 0.2 mm to 0.8 mm.
 20. The apparatus according to claim 17, wherein the workpiece is placed between the at least one plate electrode and the counter electrode.
 21. The apparatus according to claim 17, wherein the workpiece is one of conductive, semiconductive and non-conductive.
 22. The apparatus according to claim 17, further comprising a chamber for treating the workpiece under a working gas environment.
 23. The apparatus according to claim 22, wherein the chamber includes at least one gas input opening and at least one gas output opening.
 24. The apparatus according to claim 17, wherein the capillary formed in the dielectric body is located to form a parallelogram shape.
 25. A method of treating a workpiece using a plasma discharge apparatus, the method comprising: placing the workpiece in close proximity to the apparatus, wherein the apparatus includes at least one plate electrode for receiving a power source, a dielectric body having first and second sides, wherein the first side is coupled to the at least one plate electrode and the second side has at least one capillary extending to a direction of the first side of the dielectric body, and a counter electrode electrically coupled to the power source and a ground; applying a potential to the at least one plate electrode and the counter electrode; and generating a plasma discharge out of the capillary.
 26. The method according to claim 25, wherein the workpiece is in a continuous motion by placing the workpiece on a conveyer that passes under the plasma.
 27. The method according to claim 25, further comprising providing a working gas in close proximity to the workpiece. 